An Effective Method of Solving Anisotropic Nonlinear Periodic Electric Field in Oil-Paper Insulation under the AC-DC Hybrid Voltage

In this paper, the frequency finite element method, combined with fixed point method and linearization method, is adopted to compute the anisotropic nonlinear periodic electric field in oil-paper insulation under the AC-DC hybrid voltage, which contains many high order harmonics. The field equation is derived based on the qua-static field theory, and the formula of selecting fixed-point conductivity is proposed. The proposed algorithm is used to analyze the anisotropic nonlinear periodic electric fields of an typical model of converter transformer under the AC-DC hybrid voltage and the results show that the anisotropism of the oil-immersed paper has significant effects on the distributions of potential.